Known in the art are methods of producing thiophene and its derivatives by interacting various organic compounds, such as crotonic acid, pyrrol, furan, ethylene, propylene, butylene, butane, acetylene, etc., with sulphur-containing compounds, for example, hydrogen sulphide.
But it is difficult to accomplish the majority of the known methods even under laboratory conditions. This is associated, mainly, either with a high cost of the initial components or with technological difficulties which arise in the process and especially when isolating thiophene from the reaction mixture.
Also known in the art is a method of producing thiophene by isolation thereof from a benzene fraction of coal-tar chemicals. This method is technologically complicated.
Likewise known in the art is a method of producing thiophene by interacting diacetylene with hydrogen sulphide in an aliphatic alcohol or acetone in the presence of sodium hydroxide (pH=9-10) at a temperature of 20.degree.-80.degree. C.
Also known in the art is a method of producing thiophene by interacting diacetylene with sodium sulphide in the form of a saturated aqueous solution in an aliphatic alcohol or in acetone.
The above methods of producing thiophene from diacetylene are disadvantageous in that the yield of the final product is low (to 20% of theory). Therefore, the known methods have found application neither in industry nor in preparative chemistry. In addition the use of low-boiling aliphatic alcohols as a solvent makes the separation of thiophene difficult.